Essay by PaperNerd ContributorUniversity, Master's February 2002

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1. The difference between EPSP and an IPSP is that EPSP helps a postsynaptic neuron's ability to reach an action potential and IPSP reduces the ability to reach an action potential. In determining which will be generated at the postsynaptic membrane, the axon hillock counts the number of EPSP and IPSP. If there are more EPSP than IPSP, enough to reach threshold, you will get an action potential. If on the other hand IPSPs dominate the count hyperpolarization will occur.

2. Lateralization of cortical functioning is that both hemispheres of the brain have their own seperate abilities. Each hemisphere is better than the other at some functions, but neither side is better at all functions.

Cerebral dominance is a misnomer because one or the other cerebral hemisphere dominates each task. Cerebral dominance designates the hemisphere responsible for language, this doesn't mean it's the dominate side for all tasks.

3. A plexus is an interlacing network of nerve fibers.

Because of the number fo plexuses, damage to one spinal segment or root will not completely paralyze any limb muscle.

4. The white rami are only found in T1-L2 spinal cord segments, gray rami are associated with every chain ganglion from the cervical spine to the sacral region. White rami are are myelinated and the gray are not. White rami carry preganglionic fibers. Grey rami have postganglionic fibers.